UberMenu Control Panel > Main UberMenu Configuration > Submenus > Invert Submenus
By default, horizontal menu submenus will open down, and vertical menu submenus will open to the right.
To change the direction, you can use the Invert Submenus setting in the Control Panel to make the submenus open up or left
Please note this setting is experimental and was added in UberMenu 3.2